Regan administration officials and congressional leaders, already concerned about Soviet influence in Central America, have found a new cause for alarm: The region's poor and disadvantaged students are increasingly turning to the Soviet Union for college while the children of the ruling classes come to the United States.

The pattern, confirmed in two recent studies, tends to reinforce the image of the United States as the protector of the ruling elites in the region and may give the Soviets both a propaganda advantage and a corps of loyal followers for the future.

But the government, through the United States Information Agency (USIA), is launching a counterattack in the form of expanded scholarships designed to attract more low-income students to this country.

Policy-makers long have seen education as a key to building bridges to local populations. Former secretary of state Henry A. Kissinger, in his commission's report on Central America last year, noted "the important implications which the training of a country's future leaders has on its political development."

The Soviet Union is far ahead in the game. By giving generous scholarships for study in Moscow and by upgrading their higher-education system, the Soviets increased the number of Central Americans at their universities by 300 percent between 1977 and 1982, according to a study by the USIA.

In the 1983-84 school year, according to the USIA, the Soviets brought 3,030 Central American students to Moscow on full government scholarships.

By contrast, the report found, the number of Latin students coming to this country actually declined over much of the same period. The number of Central American students in this country peaked at 7,580 in 1981; two years later the number had dropped to 6,800.

But those statistics tell only part of the story. Only 226 of the 6,800 students here were sponsored by the U.S. government. The vast majority were paying their own way -- meaning that the students were disproportionately children of Central America's elite.

"While overall numbers of Central Americans studying in the U.S. are high," the USIA report concluded, "barriers for study in the U.S. by talented youth from lower socio-economic classes are very high."

"Foreign students in the United States tend to come from the wealthier families," House Majority Leader James C. Wright Jr. (D-Tex.) noted in a speech on the House floor. "They represent the economic elites of their home countries. And that fact, that skewing in favor of upper-class elites, hurts the United States over the long run."

Now the United States has launched an educational counterattack.

A USIA Central American Scholarship Initiative program, approved by Congress last year, will use $3.8 million to bring 143 undergraduate students and teachers to study at 10 colleges in the United States in the fall.

A separate program, at Georgetown University here, is targeted at high school students who show strong college potential.

Colleges must submit proposals to participate in the program by today. Sixty-nine colleges and universities have applied to be host to some of the Central American scholars.

In addition, $5.1 million will be used to bring 200 Fulbright scholars to this country. During fiscal 1984, 53 scholars and students were brought here under the Fulbright program.

Also, $302,000 will allow 27 new participants in USIA's International Visitors Program.

According to Michael G. Stevens, the USIA program director, the undergraduate student program is one of a kind because it aims to attract lower-income and disadvantaged students. "It's to cast a different kind of a net than we had in the past," he said. "It's directed to students from non-elite backgrounds.

"Most students, if given a choice, would prefer to study in the West rather than in the Soviet Bloc," he said. "But the Soviet program is well-crafted. They know their market segment -- students who don't have other prospects. The Soviets have cast their net very intelligently, from their perspective."

Students returning to Central America after a Soviet education will be grateful to Moscow and, perhaps even more importantly, will form a cadre trained in Soviet technology and engineering, among other things, Stevens said.

Moreover, he said, if their degrees are not readily recognized at home by western-oriented institutions, they may become alienated and anti-West, an educated underclass that could threaten the region's social structures.

Wright has introduced legislation to expand U.S. government support to underprivileged students from other developing countries.

"It brings low-income students to the United States, thereby broadening the base of popular support the United States could have in developing countries," he said.

The stepped-up interest represents the first fruition of recommendations by Kissinger's bipartisan commission.

In the commission's report, Kissinger wrote, "It is imperative to offer young Central Americans the opportunity to study in the United States, both to improve the range and quality of educational alternatives and to build lasting links between Central America and the United States."

Compared to Kissinger's initial recommendation -- for $100 million to bring 10,000 Central American students here -- the recent flurry of activity seems paltry.

However, higher sums initially requested were scaled back, as some members of Congress complained about how it would seem giving more money for foreign students to come here when the administration was proposing drastic cuts in college aid to U.S. citizens.

University officials said privately that they found it ironic that the administration was trying to step up its scholarly exchanges with Central America even as the State Department has been invoking federal immigration law to keep out or delay visas for many Latin American scholars with leftist or otherwise controversial views.

Those affected this year include Nicaraguan Minister of Culture Ernesto Cardenal, who was invited to speak at several U.S. universities, and Felicidad Esperanza Alas, a Salvadoran schoolteacher in a delegation of Latin American teacher-union leaders.

Efforts are under way in Congress to rewrite parts of that law.